based on a video made by Michael Stevens of VSauce.
I’ve done a couple of posts concerning outer space, so let’s have another. Something that has been on my mind lately is the question: If you could go into orbit and float around, would you be completely free from the influence of gravity? Not really. According to Michael Stevens (Stevens),
Astronauts orbiting around the earth are feeling pretty much the same gravitational pull you and I are feeling right now. The major difference is that those astronauts are falling, constantly, towards earth, but their angular velocity is so large that they’re falling just as fast as earth curves away from them.
And to take this original question further, what would happen if you were to take a loaded gun with you into outer space, and fire it. Would it even fire, and further, what would the bullet do? We’ll get into all of that here in a little bit, but first…
Back to the Astronauts:
The scenario describes by Stevens is precisely what Newton’s Canon teaches us. Minute Physics on YouTube explains what Newton’s Canon is so that it is quite easy to understand. Basically, gravity makes things want to fall, and Newton realized that this makes objects fall to the earth at the same right no matter how fast they are moving horizontally. This is known as relativity. In order to fall and successfully miss the earth (unless you dug a tunnel which I’ll describe what would happen if you did that at the end of this post) you’d have to be traveling at about 17,000 mph, or 5 miles every second. Newton’s experiment involved the earth, but if you shot a cannon on the moon, or a smaller body, it wouldn’t have to travel nearly as fast to complete its orbit. Now,
If you had a powerful enough gun on the moon, and fired it away from you, you could shoot yourself in the back of the head by the same bullet. Minute Physics calculated that the bullet would have to be traveling about 1600 m/s, which happens to be exactly how fast the Paris Gun fires. Stevens says:
(The Paris Gun) is a powerful gun, it’s no “squirt gun.” But if you had a squirt gun out there in space, and you had a stream of water at the sun, how much water would it take to put out the sun?
Well the issue with that is that the Sun is not a big ball of hydrogen on fire, but is instead powered by fusion. Because of this, if you added water to the sun, it wouldn’t get darker. Instead, it would get brighter. However, it would also burn faster, meaning that the life of our solar system would be shorter. Stevens says:
If you were to add twenty solar masses of water to the sun, you would decrease its life expectancy from the current 5 billion years to only a few hundred million more years.
There is however, a faster way to put out the sun. Take the water, and instead of just putting in on the sun, shoot/place it in a manner so that it is scattered. This will take away the critical density that is needed for fusion to occur. No matter which option you choose, both choices would be a disaster. Literally. Dis (which means against) and aster (which means star). What would happen if you could magically appear somewhere else in space and avoid this disaster?
Well, if you shoot a bullet out of a gun, that bullet (in space) would be forever alone. According to Minute Physics,
That’s because the universe is expanding, and if you were a few mega-parsecs away from the nearest galactic cluster, on average those galaxies would be 200 kilometers away from you every passing second. In space terms, 200 kilometers per second is pretty slow. It’s barely as fast as the solar system orbits the milky way, and stars closer to the center of the galaxy can orbit 10 times faster.
If you shot a bullet, it travels one km/s which is far slower than the 200km/s the receding galaxies would be traveling. This means that the bullet would never catch the other galaxies and would be forever alone.
All of this talk may make you realize how tiny and seemingly insignificant we are compared to the rest of the universe, but you should also realize how close together we all are.
Thank you for reading this,
Austin Duncan, Author
Sources are present in the links found throughout this article. The concept of this entire post and its content is highly borrowed from Michael Stevens from VSauce. Look him and his channel up, it’s really interesting. If you want to keep reading about the subject I said I would finish explaining early in this post, keep reading below.
Now, back to the topic I said I would answer earlier in this post:
Another question is, what if we dug a hole through the center of the earth (I know it’s not possible, but just go along with me here) and jumped in? Well you probably wouldn’t make it very far, due to the Coriolis Effect. You know, the reason a ball curves weirdly if you toss it while riding a merry-go-round, or why hurricanes only spin counter-clockwise in the northern hemisphere. According to Minute Physics:
At the equator, the Earth and you on it, is rotating eastwards at 1670 km/hr. As you go deeper, the bits of earth around you are still spinning around once per day, but they don’t have as far to travel so they’re going at slower and slower speeds.
If you jumped into a vertical shaft, you’d soon be traveling east faster than the rock around you, so that after falling only a few kilometers, you’d crash into the eastern wall. It might not be a disaster, but some miners near Lake Superior tried to test this by dropping cannon balls down a mile-long shaft, and the balls never reached the bottom.
So let us ask a different question. What if the tunnel went from the North to South pole, so that the Coriolis Effect no longer applied? Also, let’s take out any air resistance or friction. Again, Minute Physics explains this very well saying:
Since the earth’s mass is more concentrated near the middle, gravity would actually pull you down with the same amount of force for the first 3,000 km. This familiar constant force would accelerate you until you were falling 8 kilometers every second, and the trip half-way to the middle of the earth would only take 13 minutes. Soon after, you’d reach the earth’s outer core, and this is the point in your journey where the pull of gravity would be strongest. But only slightly stronger than the force we’re used to on the surface. As you continue to fall, so much of the earth’s mass would be above you that it would seriously begin to cancel out the attraction of the mass below, and the downward pull would weaken as you reach the center. Here, you would experience no gravitational pull at all.
So simply put, at the center of the earth, the gravitational pull of the earth on your body would be pulling from all directions, instead of just the downward force we’re used to. Once you passed the center of the earth (traveling about 6 miles per second) the process would reverse and you’d continue on your journey slowly at first, and the more quickly until you reached the other side and could step out comfortably. All of this would only take about 37 minutes.
The deepest we’ve been able to dig is the Kola Superdeep Borehole. It only goes down 12 kilometers. They were forced to stop because the temperature was too high, about 180°C (or 358° F). This is pretty much the problem with digging a hole through earth, it’s too hot. But, what if earth wasn’t that way, and was instead hollow, but weighed the same?
Minute Physics yet again answers this by saying:
Well, with (the earth’s) entire mass concentrated in the thin shell right under our feet, the earth wouldn’t have a magnetic field anymore, because that comes from the molten iron core. So, we’d be totally vulnerable to radiation from the solar wind and solar storms and this means we’d see the aurora everywhere…And if you jumped inside the hollow earth to escape the storms, well, gravity from the different spherical earth’s shell would perfectly cancel out and you’d float freely about inside as if the earth weren’t there at all.
If this were the case, you better have a space suit or something because there isn’t enough air on earth to fill up the hollow inside as well. Outside of earth, things would still appear to be the exact same, gravity wise.
- Can You Own Outer Space? (theinformate.wordpress.com)
- If (theinformate.wordpress.com)
- What Color is a Mirror? (theinformate.wordpress.com)
- Six Careers in which Knowledge of the Coriolis Effect is Essential (geography.answers.com)
- Day 26: Weightlessness ≠ No Gravity (noschese180.wordpress.com)
- Understanding the Coriolis Effect (geography.answers.com)